Place all dry ingredients into the bowl of a food processor (all-purpose flour through salt); top with cover, and process for 10 seconds.
Cut butter into pieces and add to the bowl along with the lemon zest and juice; cover and process until just combined. Transfer mixture to a piece of waxed paper and form into a ball.
To make the cookies, pinch off pieces of dough, form into balls and place on a cookie sheet lined with parchment paper. Flatten the dough balls using the palm of your hand. If desired, sprinkle the top of each cookie with a little additional granulated sugar. Bake in a preheated 350-degree oven for 10 to 12 minutes or until lightly browned. Transfer to a cooling rack and cool completely.